The burden of hyponatremia: Infants born at <28 weeks’ GA the incidence of hyponatremia was 64%. Infants born between 29 to 34 weeks the incidence between 33%–70%

Why hyponatremia in preterm: At the time when the majority of preterm infants are born, renal development is still ongoing and renal function is accordingly immature. Preterm neonates have been shown to have a low glomerular filtration rate (GFR) compared with term neonates, and the tubules excrete high amounts of sodium. Furthermore, compared with babies born at term, preterm neonates may demonstrate a slower progression in renal functional maturation after birth.

Proposed Mechanism Accounting for Impaired Growth in Sodium Deficiency: More than 20 years ago Haycock described a mechanism accounting for sodium regulation of cellular growth, attributing it to the Na–H antiporter. This pathway is now widely accepted as an important regulator of tumour cell growth and likely plays an important role in sodium deficiency-induced growth impairment. Activation of the antiporter leads to an increase in intracellular pH and is essential, or at least permissive, for the development of a cell proliferative response. Reduced extracellular sodium availability inhibits hydrogen extrusion, and thus promoting intracellular acidosis and this is the mechanism responsible for the impaired growth receptors’ function.

Other problems with hyponatremia: Neonate with hyponatremia had longer hospital stays and higher risks of BPD and ROP

requiring treatment.Hyponatremia lasting at least 7 days significantly associated with periventricular leukomalacia, and extra-uterine growth retardation.

Importance of oral sodium supplementation: Growth in the early neonatal period in premature infants affects neurodevelopmental

outcomes. Sodium is important for growth, yet fortified human milk and commercial formulas often fail to provide the 3–7 mEq/kg/d current sodium intake recommendations for preterm infants.

Need for our study: Though sodium level has implications on short and long term outcomes, there is no consensus worldwide. There are no trials in India regarding routine sodium supplementation in preterm to the best of our knowledge.

Methodology: Study drug will be prepared by the pharmacist under strict aseptic conditions using laminar flow by adding analytic sodium to sterile water to make the desired concentration of 15% saline Preparation of drug planned to do biweekly by the pharmacist. The prepared drug will store in 10ml syringes at room temperature. (we checked for stability, the drug does not have any precipitation or physical changes)Control group which will receive 0.45% saline(commercially available) also keep as 10

ml aliquots. The study drug was initiated after obtaining consent from parents when the baby reaches 100TCI of feeds and administered with every feed up to 34 weeks PMA. Infants randomized to the intervention arm receive of 15% sodium chloride for a total of 4 mEq/ kg/d in divided equal volume in 12 feeds daily. While infants in the placebo arm received the same volume of sterile 0.45%NS divided the equal volume into 12 feeds daily. Started with dosage based on weight at birth. After crossing birthweight dose will change every 3rd day as per on working weight. 1st sodium sampling will be done when the neonate reaches100TCI between day 5 to 9, and if value <145 will include in the study. After reaching 100 TCI if sodium >145 then will do daily sodium monitoring until day 9. After day 9 still sodium >145 then the neonate will be excluded from study. After starting study 1st sample will be done between 3 to 5 days, later all samples will be done on every Sundays. Comprehensive and weekly weight gain velocities (g/kg/d) were calculated. Weight, length, and head circumference measurements at birth and weekly until 34 weeks PMA will be plotted on Fenton growth charts